JP2023046986A - Fixing device and image forming apparatus - Google Patents

Abstract

To provide a fixing device that can efficiently and effectively detect the remaining amount of a cleaning web without using a special cleaning web but using single detection means.SOLUTION: A fixing device comprises a fixing member 30 and a pressure member 31 that forms a fixing nip part N at a portion between the pressure member and the fixing member 30, and fixes a toner image to a recording medium P. The fixing device comprises cleaning means 122 that removes a residual toner attached to a surface of the fixing member 30. The cleaning means 122 includes a cleaning web 41 that sweeps off the surface of the fixing member 30, a web holding member 44, a take-up member 46, a pressing member 45, and single detection means that detects the remaining amount of the cleaning web 41 held by the web holding member 44. The detection means has a filler 40 that is displaced according to the remaining amount of the cleaning web 41 and a sensor 42 that detects the filler 40, and detects a web near-end state and a web end state.SELECTED DRAWING: Figure 4

Description

The present invention relates to fixing devices and image forming apparatuses.

Conventionally, as a fixing device of an image forming apparatus, a recording medium (paper) bearing a toner image is passed through a fixing nip formed by a fixing member having a heating means and a pressure member to apply heat and pressure. It is known to fix a toner image on a recording medium by means of
Also known is a configuration in which a cleaning web that can be wound up is pressed against the surface of the fixing member to clean the surface of the fixing member.

The cleaning means includes, for example, a web holding member to which the terminal end of the cleaning web is fixed, a winding member to which the leading end of the cleaning web is fixed and which rotates to wind the cleaning web, and a pressing member that presses the cleaning web against the fixing member. A configuration is known that includes a member. By winding up the cleaning web with the winding member, the surface of the fixing member can be wiped with a new web fed out from the web holding member. Therefore, the fixing member can be cleaned satisfactorily without deteriorating over time.

Such a cleaning device has a mechanism for detecting the remaining amount of the cleaning web wound around the web holding member or the used amount, and warning to replace the cleaning web with a new cleaning web when the remaining amount is small. is known (see, for example, Patent Document 1).

Continuing the operation of the apparatus with an insufficient remaining amount of the cleaning web may lead to problems such as deterioration in image quality and damage to the drive motor and gears. Further, if printing is continued after the warning to replace the cleaning web is displayed, there is a possibility that the cleaning web will completely run out and an error will cause an emergency stop of the apparatus.
Regarding the remaining amount of the cleaning web, it is required to be able to detect the web near-end state in which the cleaning web is about to run out and the web end state in which the cleaning web runs out.

In order to address such a problem, the apparatus disclosed in Japanese Patent Application Laid-Open No. 2002-200000 discloses a configuration in which a web remaining amount detection sensor detects a notch indicating the remaining amount provided in the cleaning web (fixing web). It is described that the operator can change the web at an appropriate timing by making it possible to display the predetermined remaining number of copies corresponding to the notch.

In the apparatus of Patent Document 1, it is necessary to use a cleaning web having cutouts corresponding to the remaining number of copies. Therefore, there is a problem in terms of cost of consumables. Moreover, it is necessary to accurately arrange the sensor at a position where the notch can be detected, and there is a problem that it is not easy to obtain sufficient detection efficiency and detection effect with a single detection means.

SUMMARY OF THE INVENTION Accordingly, it is an object of the present invention to provide a fixing device capable of efficiently and effectively detecting the remaining amount of a cleaning web by a single detecting means without using a special cleaning web.

In order to solve the above problems, a fixing device of the present invention includes a fixing member, which is a rotating body heated by a heating means, and a pressure member forming a fixing nip portion between the fixing member and the fixing member. A fixing device for conveying a recording medium bearing an unfixed toner image to a fixing nip portion and fixing the toner image on the recording medium, the fixing device comprising cleaning means for removing residual toner adhering to the surface of the fixing member, The cleaning means includes a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be sent out, a winding member for winding the cleaning web, and a cleaning web for fixing the cleaning web. A pressing member that presses against a member, and a single detection means for detecting the remaining amount of the cleaning web held by the web holding member, wherein the detection means is displaced according to the remaining amount of the cleaning web. and a sensor that detects the filler, and detects a web near-end state in which the cleaning web is about to run out and a web end state in which the cleaning web runs out.

According to the present invention, it is possible to provide a fixing device capable of efficiently and effectively detecting the remaining amount of cleaning web by a single detecting means without using a special cleaning web.

1 is a schematic configuration diagram showing an example of an image forming apparatus according to the present invention; FIG. 1 is a schematic perspective view of the appearance of a fixing device according to the present invention; FIG. 1 is a schematic perspective view of the appearance of a fixing device according to the present invention; FIG. 1 is a schematic diagram showing an example of the configuration of a fixing device according to the present invention; FIG. FIG. 4 is an explanatory diagram showing the positional relationship between the remaining amount of cleaning web and the detection means; FIG. 4 is an explanatory diagram showing the positional relationship between the remaining amount of cleaning web and the detection means; FIG. 4 is an explanatory diagram showing the positional relationship between the remaining amount of cleaning web and the detection means; FIG. 4 is an explanatory diagram showing the positional relationship between the remaining amount of cleaning web and the detection means;

A fixing device and an image forming apparatus according to the present invention will be described below with reference to the drawings. In addition, the present invention is not limited to the embodiments shown below, and can be changed within the scope of those skilled in the art, such as other embodiments, additions, modifications, deletions, etc. is also included in the scope of the present invention as long as the functions and effects of the present invention are exhibited.

[Image forming apparatus]
An embodiment of an image forming apparatus according to the present invention will be described with reference to FIG.
FIG. 1 is a schematic configuration diagram showing an image forming apparatus, specifically a copier printer capable of forming a monochrome image. It also functions as a printer by connecting to a PC.

Since the image forming apparatus of the present embodiment is a copying machine, it has a document reading unit that functions as a scanner. may be omitted.

The schematic configuration and operation of the image forming apparatus of this embodiment will be described below.
2. Description of the Related Art An image forming apparatus has a scanner containing an illumination device, an optical system, a CCD image sensor, and the like.
An automatic document reader (hereinafter referred to as an "ADF unit" (ADF: Auto Document Feeder)) 100 is provided above the scanner. The ADF unit 100 automatically conveys the document and sends it to the reading surface of the contact glass.

The operator sets a document on the ADF unit 100 with an integrated pressure plate, selects a mode using the function selection keys on the operation panel, and operates the numeric keypad, function keys, etc. while confirming the contents displayed on the liquid crystal screen to select the desired image. Set formation conditions.

An image signal read by the document reading unit 102 is A/D (Analog/Digital) converted by an SBU (Sensor Board Unit), and then irradiated as laser light from a laser writing unit 107 . The laser light is condensed by the cylinder lens of the laser writing unit 107 and is line-scanned in the main scanning direction by the polygon mirror to form an electrostatic latent image on the photosensitive drum 108 .

The developing unit 110 includes a drum cleaning unit 105 and a charging charger 106 around the photosensitive drum 108 . A charging charger 106 is used to charge the photosensitive drum 108 .
A high voltage is applied to the charging charger 106 from a PSU (Power Supply Unit) through a receptacle, an electrode terminal, a conductive bearing, and the like.

The toner supplied from the toner supply unit 109 as needed and the developer prefilled in the developing unit 110 are agitated and mixed by the internal conveying screw and conveyed to the developing roller. The toner electrostatically attracted by the magnetic force is negatively charged.

The two-component developer carried on the developing roller is regulated in an appropriate amount by developer brush regulating members such as a doctor blade and a casing disposed below the developing roller, and then the triboelectrically charged toner in the two components is biased. The voltage causes it to move onto the photoreceptor drum 108 and selectively adhere to the electrostatic latent image.

The toner density inside the developing unit 110 is detected from the charge amount by a toner density sensor arranged at the bottom position.
Untransferred toner remaining on the photoreceptor drum 108 after transfer is scraped off by a cleaning blade provided in the drum cleaning unit 105 and transported to and collected in a waste toner bottle 119 .

An inlet seal made of mylar or a sponge-like material is appropriately provided around the developing unit 110 to prevent toner scattering.

A visible image formed by toner on the photosensitive drum 108 is temporarily transferred onto the intermediate transfer belt unit 113 .
The recording medium conveyed by the paper conveying portion 114 and passed through the registration roller portion is positively charged from the transfer portion when passing through the nip between the photoreceptor drum 108 and the intermediate transfer belt unit 113. Toner is transferred.

The recording medium (paper) onto which the toner has been transferred is conveyed to a fixing device (fixing unit) 121, where a certain temperature and pressure are applied to thermally fuse the toner image.
A fixing roller in the fixing device 121 is provided with a thermistor to detect the surface temperature, and ON/OFF control of the heater is performed. Thermistors may be contact or non-contact. Also, a thermal fuse is provided to prevent excessive temperature rise.

The fixing device 121 of this embodiment includes at least a fixing member (fixing roller), heating means, and a pressure member. The pressure member (pressure roller) is, for example, a hollow member that rotates in contact with the fixing member and forms a fixing nip portion. Pressurization and depressurization of the fixing nip portion is controlled by a cam. A heating member may be provided inside the pressure member.
Other configurations of the fixing device 121 will be described later.

After being separated from the heating member and the fixing member by the fixing/separating plate, the recording medium to which the toner image has been thermally fused is passed through the reversing paper output unit 120, or after double-sided printing is performed according to the setting conditions, and then to the paper output tray. 125 is discharged. When a post-processing device or the like is connected, the recording medium is conveyed to the recording medium inlet of the connected device.
The image forming apparatus also includes main body moving casters 124 .

The image forming apparatus of the present embodiment performs image formation by electrophotography with the above-described configuration and operation.

[Fixing device]
Next, the configuration of the fixing device 121 according to the present invention will be described with reference to FIGS. 2 to 4. FIG.
The fixing device 121 of this embodiment is mounted so as to be able to be pulled out from the image forming apparatus shown in FIG.
The fixing device 121 of the present embodiment includes a fixing member (fixing roller) 30, a pressure member (pressure roller) 31 that contacts the fixing member 30 to form a fixing nip portion, and a recording medium ( and a separation unit 13 having a separation member for separating the paper P.

2 and 3 are schematic perspective views of the appearance of the fixing device 121. FIG.
2 shows the separation unit 13 fixed in the closed position, and FIG. 3 shows the separation unit 13 completely opened.

The fixing device 121 of this embodiment includes a fixing member 22 . In the conventional fixing device, a coil spring or the like is provided as an opening/closing assisting member 25 so that the separation unit 13 does not drop due to its own weight, and its tension maintains the weight balance during opening/closing. However, if the tension of the coil spring is insufficient, the holding force is also insufficient, and the separation unit 13 may drop due to its own weight. In contrast, the fixing device 121 of the present embodiment can fix the separation unit 13 at a desired position between the open position and the closed position by the fixing member 22, preventing the separation unit 13 from accidentally dropping or moving. can be prevented.

In the fixing device 121 of this embodiment, the operation for swinging and rotating the separation unit 13 to open and close is performed by manually moving the fixing member 22 and the operation knob 23 .
First, while pressing the urging member 26, while sliding the fixing member 22 with the left hand, the operation knob 23 is raised to the position 23a (see FIG. 2) with the right hand to release the lock, and the separation unit 13 can be opened and closed. becomes.

FIG. 4 is a schematic diagram showing an example of the configuration of the fixing device 121 according to the invention.
The fixing device 121 of this embodiment includes a fixing member 30 which is a rotating body heated by a heating unit, and a pressure member 31 forming a fixing nip portion N between the fixing member 30 and the fixing nip portion N. The recording medium P bearing the unfixed toner image is conveyed to the recording medium P, and the toner image is fixed on the recording medium P.
A cleaning unit 122 for removing residual toner adhering to the surface of the fixing member 30 is also provided.
The cleaning means 122 includes a cleaning web 41 that wipes the surface of the fixing member 30 , a web holding member 44 that holds the cleaning web 41 so that it can be fed out, a winding member 46 that can wind the cleaning web 41 , and a cleaning web 41 . to the fixing member 30 and a single detecting means for detecting the remaining amount of the cleaning web 41 held by the web holding member 44 .
The single detection means has a filler 40 that is displaced according to the remaining amount of the cleaning web 41 and a sensor 42 that detects the filler 40, and the web near-end state in which the cleaning web is about to run out and the web in which the cleaning web has run out. Detect the end state, respectively.

The toner melted at the fixing nip portion N is not entirely fixed on the recording medium P after passing through the fixing nip portion N, but part of the toner adheres to the surface of the fixing member 30 and is displaced as the fixing member 30 rotates. It will move with it. The toner transferred to the fixing member 30 adheres to the pressure member 31 in contact with the fixing member 30, the recording medium P to be passed next, and the like, thereby staining them.
In order to prevent this problem, the fixing device 121 of this embodiment is provided with a cleaning unit 122 that cleans the toner adhering to the surface of the fixing member 30 .

The cleaning means 122 includes a cleaning web 41 for wiping the surface of the fixing member 30 , a web holding member 44 , a winding member 46 and a pressing member 45 .
As the cleaning web 41, a known long web that can wipe off the residual toner on the surface of the fixing member 30 can be used, and examples thereof include non-woven fabric. Specifically, it is a fiber sheet, web, or the like, in which fibers are oriented in one direction or randomly, and the fibers are bonded by alternating current, fusion, and/or adhesion. Natural fibers include cotton, wool, hemp, pulp, and silk, and chemical fibers include rayon, nylon, polyester, polypropylene, acrylic fibers, vinylon, and aramid fibers.
The take-up member 46 is driven by the drive motor 43 and rotates in the take-up direction, whereby the unused portion of the cleaning web 41 (the portion not in contact with the fixing member 30) is sent out from the side of the web holding member 44. Moving.
By continuing the cleaning operation, the diameter of the roll-shaped cleaning web 41 wound around the web holding member 44 decreases, and the diameter of the roll-shaped cleaning web 41 wound around the winding member 46 increases.

One end of the filler 40, which is displaced according to the remaining amount of the cleaning web 41, contacts the outer peripheral surface of the cleaning web 41 wound around the web holding member 44. Displaced with change.
The displacement of the filler 40 is, for example, rotation around a fulcrum.

The positional relationship between the remaining amount of the cleaning web 41 and the detection means will be described with reference to FIGS. 5 to 8. FIG.
5 to 8 are explanatory diagrams schematically showing the cleaning means 122, where (a) in each diagram is a cross-sectional view (side view of construction) on the side of the cleaning web 41, and (b) in each diagram is , (a) is a configuration side view of the rear side when (a) is the front side of the side plate 50. FIG. In addition, in (b) of each figure, the outer periphery of the cleaning web 41 wound around the web holding member 44 and the invisible portion of the filler 40 are indicated by broken lines.

As shown in FIGS. 5 to 8, the filler 40 of the detection means has a contact portion 40a that contacts the outer peripheral surface of the cleaning web 41 wound around the web holding member 44, and a detected portion 40b that is detected by the sensor 42. and is rotated around the fulcrum 40c and displaced.

A known sensor can be used as the sensor 42 as long as it can detect the displaced filler 40. For example, an optical sensor that detects the presence and position of an object (filler 40) using light can be cited. be done.
As the optical sensor, a transmissive photointerrupter and a reflective photoreflector are preferable. The photointerrupter is a sensor in which a light-emitting portion and a light-receiving portion are arranged facing each other, and the light-receiving portion detects when the light from the light-emitting portion is blocked by the detected portion 40b of the filler passing through. The photoreflector is a sensor that reflects the light from the light-emitting portion to the detected portion 40b of the filler and detects the reflected light with the light-receiving portion.

5(a) and 5(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is new (100% unused cleaning web).
When there is a sufficient amount of the cleaning web 41 wound around the web holding member 44, the contact portion 40a of the filler is in contact with the outer circumference 41a, and the detected portion 40b of the filler is away from the sensor 42. , the sensor 42 becomes "detection OFF".

6(a) and 6(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is in the web near-end state (ratio of unused cleaning web is about 20%).
In a web near-end state in which the remaining amount of the cleaning web 41 wound around the web holding member 44 is small and the cleaning web is about to run out, the contact portion 40a of the filler contacts the outer circumference 41b. By rotating around the fulcrum 40c from the position where it was in contact with the outer circumference 41a of FIG.

7(a) and 7(b) show the positional relationship between the filler 40 and the sensor 42 when the cleaning web 41 is in a web end state (the ratio of unused cleaning web is about 2 to 3%). .
In a web end state in which the cleaning web 41 wound around the web holding member 44 is almost completely empty and the cleaning web has run out, the contact portion 40a of the filler contacts the outer circumference 41c. By further rotating around the fulcrum 40c from the position in contact with the outer circumference 41b in FIG. 6, the detected portion 40b of the filler is displaced to a position where it is not detected by the sensor 42, and the sensor 42 again becomes "detection OFF". .

FIGS. 8(a) and 8(b) show the positional relationship between the filler 40 and the sensor 42 when the percentage of unused cleaning web 41 is 0%.
There is no remaining cleaning web 41 wound around the web holding member 44 , and the contact portion 40 a of the filler comes into contact with the metal core 41 d of the web holding member 44 . Although it further rotates around the fulcrum 40c from the position where it was in contact with the outer circumference 41c of FIG. do.

As shown in FIGS. 5 to 8, in the cleaning means provided in the fixing device of the present embodiment, the sensor 42 of the detection means detects that the remaining amount of the cleaning web 41 held by the web holding member 44 is sufficient. Off, on when the web is near-end, and off again when the web is at the end.

The filler 40 is not detected by the sensor 42 when the remaining amount of the cleaning web 41 is sufficient, and is displaced to a position detected by the sensor 42 in the web near-end state, and displaced to a position not detected by the sensor 42 in the web end state. do.

That is, the signals when the detected portion 40b of the single filler 40 is before, during, and after passing through the single sensor 42 are respectively detected in the sufficient remaining amount of the cleaning web 41 and in the web near-end state. , the remaining amount of the cleaning web can be efficiently and effectively detected by a single detection means without using a special cleaning web.

The fixing device of this embodiment includes a driving motor 43 for a winding member 46 and a control means 11, as shown in FIG.
Further, means for detecting changes in the current value accompanying torque fluctuations of the driving motor 43 is further provided, and the amount of the cleaning web 41 wound on the winding member 46 is calculated from changes in the current value. ) can be compared with the state of the remaining amount of the cleaning web 41 detected by ).

By comparing the torque fluctuation of the drive motor 43 and the detection result of the sensor 42, the detection accuracy of the remaining amount of the cleaning web 41 can be further improved.

It is preferable to correct the current value associated with the torque fluctuation of the drive motor 43 according to at least one of the temperature condition, the value of the power supply voltage, and the horizontal state of the apparatus.

Alternatively, initialization may be performed when the cleaning web 41 is replaced with a new one, the current value immediately after the start of use (initial) is detected, and fluctuations in the current value are corrected using this value.

The fixing device of the present embodiment having the above-described configuration can detect the remaining amount of the cleaning web easily by a single detection means while preventing cost increase and malfunction without using a special cleaning web. Efficiently and effectively detectable.

30 fixing member 31 pressure member 40 filler 40a contact portion 40b detected portion 40c fulcrum 41 cleaning web 42 sensor 43 drive motor 44 web holding member 45 pressing member 46 winding member 50 side plate 121 fixing device 122 cleaning means

Japanese Utility Model Laid-Open No. 5-90505

Claims (7)

A fixing member, which is a rotating body heated by a heating means, and a pressure member that forms a fixing nip portion between the fixing member and the fixing member, and conveys a recording medium bearing an unfixed toner image in the fixing nip portion. and a fixing device for fixing a toner image on the recording medium,
cleaning means for removing residual toner adhering to the surface of the fixing member;
The cleaning means includes a cleaning web for wiping the surface of the fixing member, a web holding member for holding the cleaning web so as to be sent out, a winding member for winding the cleaning web, and a cleaning web for fixing the cleaning web. a pressing member that presses against a member; and a single detection means that detects the remaining amount of the cleaning web held by the web holding member;
The detection means has a filler that is displaced according to the remaining amount of the cleaning web and a sensor that detects the filler, and is in a web near-end state in which the cleaning web is about to run out and a web end state in which the cleaning web runs out. A fixing device that detects each of The sensor of the detection means is turned off when the remaining amount of the cleaning web held by the web holding member is sufficient, turned on when the web is near-end, and turned off again when the web is in the end state. The fixing device according to claim 1. The filler is not detected by the sensor when there is a sufficient remaining amount of the cleaning web, is displaced to a position where it is detected by the sensor when the web is near-end, and is not detected by the sensor when the web is at the end. 3. The fixing device according to claim 1, wherein the displacement is . 4. The fixing device according to claim 1, wherein the sensor is a photosensor. A driving motor for the winding member and means for detecting a change in a current value associated with a torque fluctuation of the driving motor are further provided, and the amount of the cleaning web wound on the winding member is determined from the change in the current value. 5. The fixing device according to claim 1, wherein the remaining amount of the cleaning web is calculated and compared with the state of the remaining amount of the cleaning web detected by the detection means. 6. A fixing device according to claim 5, wherein the current value associated with the torque fluctuation of said drive motor is corrected according to at least one of a temperature condition, a power supply voltage value, and a horizontal state of the device. An image forming apparatus comprising the fixing device according to claim 1 .

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